Structure and properties of hydrophilic polymers and their gels. XI. Microsyneresis in swollen poly(ethylene glycol methacrylate) gels induced by changes of temperature

Dušek, Karel; Sedláček, B.

doi:10.1135/cccc19690136

Cited by 40 publications

(15 citation statements)

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“…Prior to the swelling experiments conducted with MMA/MAA gels at a molar 11--.# composition of 78/22 mole%, gels at various comonomer ratios were synthesized; i. however, at the lower limit of 70/30 mole% MMAIMAA the gels appeared cloudy and white in color, indicating phase separation (19)(20)(21). Gels synthesized at a higher concentration of MAA also showed similar turbidity.…”

Section: Methyl Methacrylate Gelsmentioning

confidence: 81%

Buffer effects on aqueous swelling kinetics of polyelectrolyte gels

Chou

Blanch

Prausnitz

et al. 1992

J of Applied Polymer Sci

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Electrolytes are often added to a gel‐swelling medium under the assumption that the important conditions which characterize swelling rates are the solution pH and ionic strength, with little emphasis on the nature of the electrolyte. Previous research by Siegel et al. has indicated that the presence of the un‐ionized acidic form of an electrolyte buffer is a primary rate determinant for swelling of a polybase gel. A systematic swelling study on two separate gels, 2‐hydroxyethyl methacrylate copolymerized with methacrylic acid (HEMA/MAA) and N,N‐dimethylaminoethyl methacrylate (HEMA/DMA), has been performed to investigate the influence of the concentration of the un‐ionized buffer by three principal factors: (1) total buffer concentration, (2) solution pH, and (3) buffer pKa. Swelling and deswelling kinetics were obtained. In the presence of an electrolyte buffer, a dramatic swelling rate increase is observed for the HEMA gels, with substantial gains in rate obtained as total buffer concentration rises. Results also emphasize that to enhance swelling kinetics, the pH must be such that the buffer is essentially un‐ionized.

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Section: Methyl Methacrylate Gelsmentioning

confidence: 81%

Buffer effects on aqueous swelling kinetics of polyelectrolyte gels

Chou

Blanch

Prausnitz

et al. 1992

J of Applied Polymer Sci

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“…The “transparent gels at all water contents” were thus formed from a mixture of poly(ethylene glycol)-monomethacrylate and poly(ethylene glycol)-dimethacrylate [70, 71]. This is not to be confused with poly(ethylene glycol methacrylate) or polyglycolmonomethacrylate, which are simply poly(HEMA) [72]. Unlike PEG-based hydrogels, the poly(HEMA) hydrogels were cloudy at high water contents.…”

Section: Instructive Examples Of Liquid-liquid Two Phase Systemsmentioning

confidence: 99%

Liquid–liquid two-phase systems for the production of porous hydrogels and hydrogel microspheres for biomedical applications: A tutorial review

2011

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Macroporous hydrogels may have direct applications in regenerative medicine as scaffolds to support tissue formation. Hydrogel microspheres may be used as drug delivery vehicles or as building blocks to assemble modular scaffolds. A variety of techniques exist to produce macroporous hydrogels and hydrogel microspheres. A subset of these relies on liquid-liquid two phase systems. Within this subset, vastly different types of polymerization processes are found. In this review, the history, terminology and classification of liquid-liquid two phase polymerization and crosslinking are described. Instructive examples of hydrogel microsphere and macroporous scaffold formation by precipitation/dispersion, emulsion and suspension polymerizations are used to illustrate the nature of these processes. The role of the kinetics of phase separation in determining the morphology of scaffolds and microspheres is also delineated. Brief descriptions of miniemulsion, microemulsion polymerization and ionotropic gelation are also included.

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“…As soon as PHEMA proved to be a well suited material for ophthalmology, it was subjected to complete studies of its behavior during polymerization including studies of dilution effect on the limits of perfect optical clarity . These limits are given by thermodynamic factors and are related to χ‐syneresis in the PHEMA polymerizing in particular diluents . Syneresis was a term coined for phase separation in swollen gels or during their formation occurring in macro‐ or microform caused by deterioration of solvent power (χ‐syneresis) or by increase in crosslink density (ν‐syneresis).…”

Section: Introductionmentioning

confidence: 99%

The Manifold Varieties of Poly(2‐Hydroxyethyl Methacrylate) Hydrogels−IPNs

Dušková‐Smrčková

Sadakbayeva

Steinhart

et al. 2017

Macromolecular Symposia

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Summary The interpenetrating network structure was used to control mechanical properties of hydrogels based on poly(2‐hydroxyethyl methacrylate) (PHEMA) (first network (A) or second network (B)) and poly(glycerol methacrylate) (PGMA) (network B). In order to understand the structure, mechanical and swelling properties of sequentially made IPN hydrogels, the swollen PHEMA network microstructure and its formation was investigated by means of swelling and SWAXS experiments. Visually clear and microscopically homogenous hydrogel networks based on poly(2‐hydroxyethyl methacrylate) revealed presence of domains of size 1–10 nm formed during polymerization in the presence of water. The study was carried out to understand conditions under which the hydrophobic interactions are operative and their effect on the microstructure as well as how they change when the double network structure is introduced. The morphologies of network A ranged from homogenous, non‐porous, and optically clear gels, to macroporous gels resulting from phase separation and offering fused‐sphere morphology. A cryogel characterized by large elongated and partially interconnected pores of tens to hundreds micrometers were another object for comparison. In most cases, an increase of tensile moduli and improvement of ultimate tensile properties was achieved. A surprisingly high increase in true strength (by a factor of 10 – 30) was achieved when the macroporous PHEMA network A was reinforced by weak PHEMA or PGMA networks B. All these weakly crosslinked IPN gels were optically clear.

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Structure and properties of hydrophilic polymers and their gels. XI. Microsyneresis in swollen poly(ethylene glycol methacrylate) gels induced by changes of temperature

Cited by 40 publications

References 0 publications

Buffer effects on aqueous swelling kinetics of polyelectrolyte gels

Buffer effects on aqueous swelling kinetics of polyelectrolyte gels

Liquid–liquid two-phase systems for the production of porous hydrogels and hydrogel microspheres for biomedical applications: A tutorial review

The Manifold Varieties of Poly(2‐Hydroxyethyl Methacrylate) Hydrogels−IPNs

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